The market for bituminous roofing product has decreased in recent years due in part to the increased use of single ply roll roofing products such as thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC) for low-sloped roofing. Compared to asphalt roll roofing, single ply products are easier to apply and therefore have lower labor costs for installation. These reduced costs have increased the popularity of single ply. Nonetheless, there is a continuous need for asphalt roll roofing and therefore a continuous call for improvements to asphalt formulations that provide for better performance characteristics.
Asphalt shingles continue to be the largest selling steep slope product, but there is a continuous call for improvement in asphalt shingles, incorporating properties that will lead to better weather resistance, whether that is hail, wind or cold. Asphalt shingles are traditionally made with air-oxidized asphalt, usually having a softening point between 195° F. and 225° F., with a penetration between 10 and 25. Use of a polymer modified asphalt imparts properties that resist hail, perform better in high winds events and can function better in all temperatures.
When formulating asphalt compositions for use in roofing products, there is a trade off when selecting the components used in a given blend. For example, some commonly used components enhance elasticity, while other additives can be used to improve rigidity where that characteristic is desired. More specifically, radial and linear styrene butadiene styrene (rSBS and LSBS) are elastomers that are often used in asphalt formulations. Both tend to improve the elasticity of the final product but are fairly expensive. Polyethylene and polypropylene plastomers and other polyolefins are also used in asphalt and they tend to increase rigidity of the final product and pricing may be less expensive. Formulating an asphalt composition can be a difficult endeavor when faced with the competing costs and functional characteristics that may be desired for the finished product.
Another consideration that is important in all aspects of commercial asphalt production is to formulate the blend in a manner that reduces the carbon footprint of the product. This can be a difficult challenge considering that bitumen forms the major component of asphalt formulations, and the finished materials must perform for many years. Using recycled materials in the asphalt formulations requires balancing of properties, compatibility and pricing.
The present invention comprises bituminous compositions and methods of manufacturing them, and bituminous roll roofing and shingle products in which the bituminous compositions are used. The asphalt roll products described herein may be applied in the various manners, including heat or torch application, cold-process, self-adhering or hot mopped.
The asphalt formulations according to the invention provide for membranes that exhibit less blistering compared to conventional formulations, impact resistance and other benefits including less susceptibility to external damage such as from scuffing.
Advantageously, embodiments of the asphaltic formulations of the present invention incorporate olefin polymers comprising polyethylene and/or polypropylene waxes that are derived from recycled content.